NOTES AND MEMORANDA. 



On the Concentric Bodies of the Thjrmus.i By Dr. B. Afan- 



ASsiEW, of St. Petersburg. Anatomical Institute at Strassburg. 

 (With Plate.) — The concentric bodies of the thymus, known as 

 Hassall's corpuscles, represent, as is well known, multinuclear 

 elements of a more or less concentric arrangement in the interior. 

 Their development and nature has been variously described by dif- 

 ferent observers. Afanassiew shows that they owe their origin to a 

 retrogressive metamorphosis of blood-vessels from whose endo- 

 thelium they are directly derived. Preparations obtained from 

 glands which, while fresh, were hardened in monochromate of 

 ammonia, then washed in distilled water and alcohol, pencilled 

 and stained in haematoxylin and ammoniacal eosin solution, show 

 all intermediary forms, viz. vascular tubes whose endothelial 

 cells are enlarged, further tubes, whose lumina appear entirely 

 plugged with these enlarged cells, and finally, vessels whose en- 

 dothelial cells possess a concentric arrangement, and partially or 

 entirely occupy the lumen. 



The presence of the blood-corpuscles within the concentric 

 bodies, already noticed by Tendrassik, is now easily explained. 

 In injected preparations of human thymus Afanassiew traced 

 the injection up to the concentric bodies and several times also 

 into them. 



The vessels whose endothelium degenerates into the concen- 

 tric bodies show a thickened wall ; this probably represents the 

 capsule which is formed round many of the concentric corpuscles. 



In the first stages of development of the gland neither 

 Afanassiew nor Professor Waldeyer could detect any concentric 

 bodies — against the assertion of Berlin, His, and Friedleben. 

 They are found most numerously during the involution of the 

 organ. It thus appears probable that the involution of the 

 gland and the development of the concentric bodies — or the 

 retrogressive change of blood-vessels — stand in an intimate 

 relation to one another. — E. K. 



' ' Archiv f. Mikroskopische Anatomie,' Bd. xiv, Heft, i, p. 1 — 6, v. la 

 Valette St. George und W. Waldeyer. 



